Snap switches are currently used in a variety of devices having a linear and/or angular motion and requiring a limit to that motion. The snap switch was disclosed by Philip Kenneth McGall, in U.S. Pat. No. 1,960,020 (incorporated by reference into this application in its entirety), filed in 1933. The McGall snap switch, however, does not include an indicator to show the state of the switch. This means that there is no indication if the snap switch is energized or not, and/or operation, meaning if the snap switch is in normally open position or in normally closed position of the snap switch. To check the state and/or operation of the McGall snap switch the operator has to use instrumentation.
A safety device monitoring system, as disclosed in U.S. Pat. No. 3,696,364 (incorporated by reference into this application in its entirety), granted to Michael R. Lavelle in 1972, was designed for use in monitoring a safety device switch, which is used in an alternating current circuit. The circuit has many components and requires a separate direct current power supply. While monitoring circuits of this type have been useful for their intended purposes, they have been limited not only by their complexity and difficulty of mounting the large number of components but also by the fact that they only monitor switch outputs, open or close, and do not monitor the switch input. In addition, they are restricted to use with monitoring alternating current circuits.
Similarly, a solid state relay having a visual contact monitor is disclosed in the 1990 U.S. Pat. No. 4,929,932 (incorporated by reference into this application in its entirety) to James P. Shipkowshi and the Eastman Kodak Company. This patent provides for a visual indication system for delivering information about the status of the output terminals of a solid state relay. Again, while these monitoring circuits have been useful for their intended purpose; they are limited to monitor output terminals in alternating current circuits only and they do not offer a means of directly monitoring a switch input at the switch itself.
Therefore there remains a need for a device that provides a direct means of indicating the state and operation of a snap switch in both alternating and direct current circuit situations without the use of instrumentation.